1. Field of the Invention
This invention relates to apparatus for generation and distribution of chemical aerosols and more particularly to apparatus used to generate and distribute such aerosols from moving vehicles.
2. Background Information
Aerosol spraying done on a large scale is performed using a sprayer mounted in the rear of a truck or utility vehicle. Spray nozzles shear a liquid chemical formulation into effective sized droplets having a mass median diameter of 5-20 microns and release these droplets into the atmosphere. Typical chemical formulations include pesticides, odor control agents, bird repellents and the like. Although the natural wind currents greatly influence travel of the spray droplets to the target, a second nozzle function is to launch the droplets in the right direction. Therefore, it is desirable to be able to move the spray nozzle head to advantageous position which takes into account the natural drift of the droplets and the adjacent topography. Prior art sprayers have long included means for adjusting the angle of output of the nozzle but such adjustments are manually made using tools and are impractical during the course of operation of the sprayer. For example, consider the situation of spraying on both sides of a one-way street. First, the street is traveled with the nozzle pointing in the direction of one side of the street. Then in order to spray the other side of the street a safe position must be found to stop the vehicle and manually adjust the nozzle direction before spraying the other side of the street. Also, when spraying along a roadway which runs along the circumference of a hillside, it is desirable to spray generally downwardly in one direction and generally upwardly in the other direction.
There is a need for an aerosol generator where the direction of droplet launch can be readily controlled by the operator of the vehicle while the machine is in normal operation and the vehicle is in motion.
A well known way of generating aerosols is with a two fluid nozzle with a first fluid generally being air at elevated pressure and the second fluid being the formulation liquid from which the aerosol is made. Two-fluid nozzles utilize the energy contained in the first fluid to convert the second fluid into an aerosol. Generally, this is done by swirling the first fluid in a cyclonic manner around a sharp edge. The second fluid, generally a liquid, is injected at the sharp edge in a controlled manner. The resulting shearing action produces droplets whose mass median diameter generally increase with increasing viscosity of the second fluid and decrease with increasing energy levels of the first fluid. An example of a prior art aerosol generator is Model Maxi Pro 4 by Curtis Dyna-Fog, Ltd., Westfield Indiana and is documented in an Operation, Maintenance and Spare Parts Manual dated November 1998.